Rising Acidity in Oceans Posts Threat to Shellfish and Humans

The acidity in the oceans is rising, which will ultimately threaten marine animals, the seafood industry, and the health of humans who consume the affected shellfish.

Oct 15, 2012

Rising acidity has negatively impacted the West Coast’s $110 million oyster industry, but it will also begin to threaten other marine animals and the seafood industry. The health of humans that eat the affected shellfish may also be at risk. Since the Industrial Revolution, the world’s oceans have become 30% more acidic. In that amount of time, the seas have absorbed 500 billion tons of carbon dioxide, which has built up in the atmosphere primarily from the burning of fossil fuels.

According to scientists, the oceans have buffered the full effects of climate change by absorbing the greenhouse gas, but the benefits of that buffer have come at a cost to marine life. Oysters, clams, and corals that rely on minerals from alkaline seawater to build their protective shells and exoskeletons have been have been especially effected. The ill effects of the changing chemistry only add to the oceans' problems, which include warming temperatures and expanding low-oxygen "dead zones."

The full brunt of ocean acidification may not hit for decades, but scientists say the only sure way to avoid the worst is to significantly reduce carbon emissions. Other scientists also have been exploring ways to restore the ocean's alkalinity through artificial means, such as spreading vast amounts of limestone or other minerals on the ocean surface, though the reality of either approach has yet to be determined.

Richard A. Feely, a chemical oceanographer for the National Oceanic and Atmospheric Administration, and a team of scientists have been tracking particularly acidic waters as they well up from the deep ocean and slosh onto the continental shelf off California, Oregon and Washington. The researchers found corrosive water in every part of the ocean that they looked. A link between the corrosive waters and the alarming rate of oyster larvae not surviving was found by scientists studying the Whiskey Creek hatchery at Netarts Bay in Oregon.

Laboratory experiments show that rising acidity is toxic to some fish larvae and can bring on bizarre behavior. It scrambles the senses of the orange-and-white clown fish making them leave their protective hiding places inside corals or sea anemones. Studies show they become deaf to the sound of predators and even attracted to the predators' scent.

Scientists have been doing experiments to determine if certain animals are more adaptable to the acidity. Gretchen Hofmann, an ecologist at the University of California, Santa Barbara, has found that purple sea urchins are far better at tolerating higher acidity than are commercially grown Pacific oysters. Studies and research will continue to take place in order to try to find a way to decrease the acidity in oceans across the globe.